Photosensitive resin compositions are composed mainly of a polymerizable compound with an ethylenic unsaturated bond, and a photopolymerization initiator, and the ethylenic unsaturated compound is usually one that can be cured by ultraviolet irradiation.
Polymerization curing requires a suitable photopolymerization initiator, with ultraviolet irradiation resulting in production of active radicals by the photopolymerization initiator, which reacts with the ethylenic unsaturated compound for polymerization.
The light source used to obtain fine lines by polymerization is usually light of 365 nm or 405 nm. In addition, since photosensitive resin compositions with sensitivity to short wavelength light sources allow fine printing, photopolymerization initiators with excellent sensitivity for 365 nm or 405 nm light sources are desired.
Such photosensitive resin compositions with sensitivity to short wavelength light sources are used in various fields including photocuring inks, photosensitive printing plates, dry film resists, color filters and the like.
Patent documents 1-4 mention oxime ester derivatives, and the use of oxime ester derivatives as photopolymerization initiators is known.
Also, Patent documents 5 and 6 describe O-acyloxime photoinitiators with higher sensitivity. However, these O-acyloxime photoinitiators are also unsatisfactory as photopolymerization initiators with 365 nm or 405 nm light sources, and even higher sensitivity is desired.